Oligomer self assembly is a major source of nanoplastic release from household plastic cutting boards

Plastic cutting boards are ubiquitous, yet the scale and health significance of their nanoscale emissions remain poorly characterized. Here we report that seven new commercial cutting boards, after a 10-minute chopping session (600 knife strikes), released 2,750–7,242 microplastics (62–164 µm) and 2.33 × 10⁷–1.12 × 10⁸ nanoparticles (104–200 nm). One month of photoaging increased nanoparticle yield by up to 963% and produced particles smaller than 50 nm. Chemical analyses revealed that 38.2–55.0% of nanoparticles from new boards were oligomer-derived, increasing to 92.7% after aging. Molecular dynamics simulations further showed that polypropylene oligomers self-assemble into spherical aggregates, whereas polyethylene forms layered structures. In zebrafish, polypropylene oligomers induced pericardial edema, bradycardia, and developmental defects at concentrations as low as 0.01 µg mL⁻¹. We integrated these release data with regional cooking statistics across 144 regions (2019–2022), identifying a global exposure peak in 2021 (7.94 × 10⁷ MPs; 1.90 × 10¹¹ NPs) driven by pandemic-era home cooking. The Americas showed the highest exposures, and high-income countries ingested more microplastics than low-income ones. This study reveals that self-assembled oligomer nanoparticles represent a major, previously overlooked contributor to dietary plastic exposure.